Thioanhydrides

Phthalic hydrazide tautomerism, 3, 4 Phthalic thioanhydride reactions, 4, 824-825... 

Benzoesaure-thioanhydrid ergibt mit einem Lithiumalanat-UnterschuB 60-70% Benzaldehyd und 70-75% Thiobenzoesaure, mit einem UberschuB 60-65% Benzylalko-hol und 65-70% Benzylthiol1 ... 

Aus Phthalsaure-thioanhydrid wird mit Aluminiumhydrid oder Diboran nahezu quanti-tativ 1,3-Dihydro-(benzo-[c]-thiophen), mit einem Lithiumalanat-UberschuB 2-Hydr-... 

The reaction of 1,2-dithiolanes with 2- and 4-picolyllithium has been examined <96PS(112)101> and the reactions of thioanhydrides such as 94 with both thiols <95JOC3964> and amines <96TL5337> have been reported. Treatment of 1,2-dithiolium salts with lithium or thallium cyclopentadienide results in formation of a variety of bi-, tri- and tetracyclic products <96LA109>. Reaction of 95 with trimethyl phosphite gives some of the desired coupling product but also the phosphonates 96 <96PS(109)557>. 

An improved synthesis of dithieno[3,2-A2, 3 -<7]thiophene 15a has been achieved from 2,3-dibromothiophene 304 (Scheme 57). Lithiation of 2,3-dibromothiophene 304 using -butyllithium followed by oxidative coupling with cupric chloride provided 3,3 -dibromo-2,2 -bithiophene 305 in 79% yield. Treatment of 305 with 2 equiv of -butyllithium in ether at —78 °C under nitrogen for 40 min and then adding benzenesulfonic acid thioanhydride and leaving the reaction mixture to reach room temperature afforded dithieno[3,2-A2, 3 -<7]thiophene 15a in 70% yield <2002TL1553>. 

Transformation of cyclic anhydrides or thioanhydrides into cis-olefins also appears a synthetically useful procedure (examples 12 and 13, Table XI). 

The heterocyclic acylphosphines (52) and (53) have been prepared by the reaction of phenylbis(trimethylsilyl)phosphine with the acid chlorides derived from phthalic and diphenic acids. The reaction of 2,3-dichloromaleic anhydride or thioanhydride with phenylbis(trimethylsilyl)phosphine gives derivatives of the 1,4-dihydro-p-diphosphorin system (54).45... 

Formate esters behave as typical carbonyl compounds in reactions with a number of ylides, eliminating phosphine oxide and forming vinyl ethers, e.g. (33).35 Stabilized phosphoranes are able to condense with the carbonyl group of cyclic thioanhydrides (34).38 Quinoline derivatives, e.g. (35), are obtained from the condensation of dicar-boalkoxy-ylides with isocyanates.37 Benzoyl isothiocyanates and keto-phosphoranes give quantitative yields of (36), which are unreactive in Wittig reactions but can be readily oxidized by selenous acid.38 The products obtained from reactions (Scheme 9) with the triazolinedione (37) depend upon the stability of the ylide used.39... 

Carbon disulphide, like the dioxide, is the anhydride (or, more strictly, thioanhydride) of a feeble acid, thiocarbonic acid, H2CS3. Moreover, between carbonic and thiocarbonic acids a number of intermediate acids are capable of existence. They are as follows ... 

These methods parallel the synthesis just described for the five-membered rings. As indicated in structures (42)—(49), standard reactions of aliphatic chemistry can be extended to the preparation of piperidines, tetrahydropyrans and pentamethylene sulfides (44 Z = N, O, S) glutarimides, glutaric anhydrides and glutaric thioanhydrides (46 Z = N, O, S) and 8-lactams, 8-lactones and 8-thiolactones (49 Z = N, O, S). 

Maleic thioanhydride and its dichloro derivative function as dienophiles. Cycloaddition with cyclopentadiene and butadiene has been reported (Scheme 155) (72AHC(14)33l). Succinic thioanhydride undergoes bis-Wittig condensations (Scheme 156) the product from ethoxycarbonylmethylenetriphenylphosphorane aromatizes to the thiophene-2,5-bis-acetic ester (454) (75LA1967). 

Phthalic thioanhydride is the benzologue of maleic thioanhydride. Its behaviour with various reducing agents is shown in Scheme 159 <72AHC(14)33l). Reaction with three equivalents of phenylmagnesium bromide followed by oxidative hydrolysis gives o-diben-zoylbenzene with only one equivalent of PhMgBr, o-benzoylbenzoic acid is formed (50%). 

Alkylidene derivatives of phthalic thioanhydride are formed as shown in Scheme 160. Reaction of phthalic thioanhydride with hot triethyl phosphite produces trafts-S -bithioph-thalide (457), probably via the carbene and phosphorane (Scheme 161) (72AHC(14)331>. Support for this mechanism stems from the fact that brief treatment of phthalic thioanhydride with triethyl phosphite in the presence of phthalic anhydride gives (458) in the presence of benzaldehyde the same reaction leads to the benzylidene derivative (456). An alternative mechanism has also been suggested, in which the penultimate step is the formation of an epoxide, which is deoxygenated to yield the product (72AHC(14)331>. 

Arsenic pentasulphide acts as an acid thioanhydride and with metallic sulphides yields salts known as thioarsenates. These may be regarded as derivatives of the following hypothetical acids ... 

Reaction of seven-membered anhydride with sodium sulfide in a 2 1 molar ratio afforded seven-membered thioanhydride and dicarboxylate in a 1 1 molar ratio (Equation 28) <1995JHC971>. The reaction of 199 gave 5,7-dihydrodibenzo[c/]thiepin-5,7-dione 200 in 77% yield. Seven-membered ring anhydrides synthesized in situ from the corresponding diacids 202 and 204 using iV-methylmorpholine and methyl chloroformate were treated with sodium sulfide in THF-HzO to form thioanhydrides 203 and 205 in 92-95% yield (Equations 29 and 30). 

A convenient route to difluoromaleic anhydride is based on the reaction of F-2,5-dihydrofuran with S03 [183], Oxodefluorination proceeds at elevated temperature and is catalyzed by trimethyl borate. F-2,5-Dihydrothiophene undergoes a similar conversion when excess of S03 is employed, the primary thioanhydride 96 is oxidized to give 97 in high yield ... 

Scherer, O. and Kluge, F. (1966) Synthese von Dichlormaleinsaure-thioanhydrid und dessen Einsatz fur die Synthese der Thiophentetracarbonsaure. Chemische Berichte, 99, 1973-1983. 

The parent compound (5) may be prepared by heating o-xylylene dibromide (a,a -dibromo-o-xylene) with sodium or potassium sulfide, usually in aqueous ethanol (see Table I for references), or by reducing phthalic thioanhydride (Section VII, B) with aluminum hydride or diborane 20 the former procedure has been used to prepare a number of derivatives of 5 (Table I). Disodium o-xylylenedimercaptide (6) can be isolated from the reaction between o-xylylene dibromide and... 

An attempt to scale up the synthesis of 2-thiophthalide by the reduction of phthalic anhydride with hydrogen sulfide gave 3,3 -bithiophthalide (106a), which arises by condensation of 2-thiophthalide (98) with phthalic thioanhydride (104) (Scheme III).118... 

More commonly, but incorrectly, named thiophthalic anhydride and sometimes referred to as phthaloyl monosulfide or o-phthalyl sulfide, this compound (104) may be prepared by heating phthalic anhydride with sodium sulfide125 or by heating phthaloyl chloride with potassium hydrogen sulfide,126 hydrogen sulfide,127 or ethanolic sodium disulfide.128 The reaction between phthaloyl chloride and hydrogen sulfide also gives phthalic anhydride and di-o-phthaloyl disulfide.127 Early attempts to prepare 104 have been described by Chakravarti.126 4-Nitrophthalic thioanhydride may be prepared by hydrolysis of 8 (R = N02 X = C1) (Section III, A).22... 

At one time phthalic thioanhydride was thought to have the structure 120a and derivatives (e.g., 120b) were thought to have similar structures. X-Ray crystallographic data for 4,5-dimethyl-... 

Phthalic thioanhydride forms charge-transfer complexes with A.A-diethylaniline and various aromatic hydrocarbons (e.g., a 1 1 complex with naphthalene).131 When oxygen and sulfur are members... 

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